P4 - Atomic Structure Flashcards

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1
Q

What happens to an electron in an atom if it releases EM radiation?

A

If they release EM radiation, they move to a lower energy level closer to the nucleus.

And if they absorb EM radiation, they move to a higher energy level and move further away from the nucleus.

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2
Q

What is the radius of an atom?

A

The radius of an atom is about 1 x 10-10 m.

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3
Q

What is the atomic number of an atom?

A

The atomic number = number of protons

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4
Q

What is the mass number of an atom?

A

Mass number = number of protons + number of neutrons.

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5
Q

What is an isotope?

A

Isotopes are variants of a particular element which have a different number of neutrons.

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6
Q

What is radioactive decay?

A

When an isotope is unstable, they tend to decay into other elements and give out radiation as they try to become more stable (they tend to try to balance protons and neutrons or get rid of excess energy) - this process is called radioactive decay.

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7
Q

What is ionising radiation?

A

Ionising radiation is radiation that knocks off atoms, creating positive ions. The three types are called alpha, beta and gamma.

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8
Q

Give three charcteristics of an alpha particle.

A

An alpha particle is two neutrons and two protons, they don’t penetrate very far into materials and are strongly ionising.

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9
Q

Give three characteristics of a beta particle?

A

A beta particle is a fast-moving electron, it is moderately penetrating and moderately ionising.

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10
Q

Give three characteristics of a gamma ray?

A

Gamma rays are waves of electromagnetic radiation, they penetrate far into materials but are weakly ionising.

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11
Q

In nucleur equations, what form are they written in?

A

Atom before decay → atom after decay + radiation emitted.

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12
Q

What is the one golden rule to remember for nucleur equations?

A

The total mass and atomic numbers must be equal on both sides.

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13
Q

Here is an example of alpha decay;

A

Uranium92238 → Thorium90234 + He24

(As you can see; the atomic number and mass number are the same on both sides)

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14
Q

So when an alpha decay occurs, what happens?

A

The atom’s atomic number reduces by 2, and its mass number reduces by 4.

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15
Q

What hapens when beta decay occurs?

A

A neutron turns into a proton and releases a fst-moving electron. So the mass number does not chnage however the proton number decreases by 1.

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16
Q

What happens when gamma rays occur?

A

Gamma rays are a way of getting rid of excess energy - so there is no change to the mass or atomic number.

17
Q

What is half-life?

A

The half-life is the time taken for the number of radiactive nuclei in an isotope to halve.

18
Q

What is irradiation?

A

Irradiation is the exposure to radiation.

19
Q

What is contamination?

A

Contamination is radioactive particles getting onto objects.

20
Q

How does a smoke detector work?

A

A radioactive material fires alpha particles at a smoke detector.

If there is smoke between the smoke detector and the radioactive material, then fewer alpha particles will reach the smoke detector. Therefore, this will set off the smoke alarm.